1. Technical Field of the Invention
The present invention relates to cutters for mineral winning machines and particularly for coal ploughs.
2. Description of Prior Art
As is known, ploughs for winning coal or other mineral in underground mine workings are equipped with replaceable cutter bits as well as special floor cutters which have two cutting edges set at an angle to one another. The floor cutters then cut the floor and the mineral face as the plough is moved along the face. The floor cutters are subjected to heavy stress and the cutters themselves are usually mounted on adjustable carriers, such as rocker levers or the like, to enable the cutting level of the plough to be adjusted. Depending on the seam conditions floor cutters need to be able to work with different cutting depths relative to the mineral face. Usually this means that a range of floor cutters defining different cutting dimensions needs to be stocked and the expense of manufacturing and storing sets of cutters is considerable. It is also known to replace worn cutters by separating a hardened tip from the main cutter body with a flame torch and then welding a new tip to the body. As an alternative it has been proposed to secure the tip provided with the cutting edge(s) to the cutter body with the aid of screws or the like. Examples of such construction are described in GB No. 1552989, DOS No. 3431495, DPS No. 1233809 and U.S. Pat. No. 4,076,318. In the case of floor cutters, it is known to fasten the cutter tip to the body with a plug-in connection and to use a pin or peg to secure the tip in place (see DPS No. 1278375). In practice, none of the above-mentioned constructions have become widely adopted in practice because they are expensive to produce and the connection between the cutter tip component and the main body component is not reliable, especially when the floor cutter is subjected to impact forces.
A general object of the present invention is to provide an improved floor cutter in which the design is simplified and the production cost is minimized. A further object is to provide a two-part cutter where the cutting edge part or tip is reliably connected to the main body in a manner permitting ready replacement of the tip. Another object of the invention is to provide a floor cutter in which a standard design can provide floor cutters with a variety of cutting depths thereby obviating the need to stock a range of cutters.